Grinding machine



Aug- 16, 1949. w. UMBDENSTO'CK K 2,479,281

GRINDING MACHINE Filed Jan. 1'?, 1946 8 SheetsSheet l INVENToR.

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GRINDING MACHINE Filed Jan. 17, 1946 v '8 sheets-sheet 2 IN1/EN TDR. ma@

Aug- 1,6, 1949- w. uMBDENsTocK 2,479,281

' GRINDING MACHINE Filed Jan. 17, 1946 8 sheets-sheet '5 .nur

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GRINDING MACHINE Filed Jan. 17, 1946 8 Sheets-Sheet 5 222 2X5 2/9 24a Z/Z/Z Aug. 16, 1949. V w. uMBDENsTocK 2.479281 I I GRINDING MACHINE Filed Jan. 17, 194e v s sheets-sheet 6 jg. f4

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GRINDING MACHINE Filed Jan. 17, 1946 8 Sheets-Sheet 7 [N V EN TOR.

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' GRINING MACHINE Filed Jan. 17, 1946 8 sheets-sheet 8 Patented Aug. 16, 1949 PATENT *OFFICE 2,479,281 GBINDING MACHINE Walter Umbdenstock, Chicago, Ill., assignor to Lion Manufacturing Corporation, Chicag, Ill.,

a corporation of Illinois Y Application January 17, 1946, Serial No, 641,790

. Y 1-'1 Claims.

The invention relatesv to improvements in grind- Y ing machines, and particularly in machines for grinding so-called stepped drills.

`1in-,object ofthe invention is to provide such a machine having a work head mounted-for rocking movement Atoward and from a grinding wheel,

the chuck for carrying the drill or work piece being also constructed for reciprocating .movement axially of the work piece Aand in timed re- .flation with the rotation of such Vwork piece.

.Another object is to provide a machine of the Ycharacter.described which maybe operated to grind raised flutes of a drill or the like with lands Aat and along the cutting edge and relieved surfaces between such lands and the rtrailing edges of the ilutes. v

, Another object is to provide a machine of the character described which may be operated to grind the shoulders between stepped portions with helical relief from the radial cutting edges to the 2,0

proper timed relations. 25

Another object consists in the provision of Vmagnetically controlled clutch means for intermittently eiecting actuation of such cam means.

Another object consists in the provision of timing means operating automatically to actuate said magnetic clutch means.

Another object consists in the provision of an automatic adjusting means to advance or retard the timing of the grinding operation'to compensate for helically formed' grooves and flutes upon a drill `or the like.

Another object is to provide means which will automatically maintain the proper synchronism and coordination betweenthe means for effecting the rocking and reciprocating movement of the work head afterstopping of the same..y

Other objects will be setl forth and made apparent in the following specication and drawings including various details of construction and arrangement of parts.

In the drawings:

Fig. lis a front view in perspective of a machine embodying my invention.' i v1 Fig. 2 is aY plan view, drawn to an enlarged scale, of a portion of the mechanism viewed from the plane of line 2-2 of Fig. 1.

i Fig. `3 is a plan view similar to Fig. 2 of the Work head and associated parts.

Fig. lY is a front elevation ofthe mechanism illustrated in Fig'. 3, portions thereof being broken away for a better understanding.

Fig. 5 is a vertical section taken along line 5-5 of liig.3'.

mechanism as viewed along the irregular lines 6--6 of Fig. 2.

Y Fig. 7 is a vertical section taken alon the lines 1 1 vof Fig. 6. Y

Fig. 8 is a vertical section taken along the lines Fig. 9 is a vertical section taken along the lines 9 9 of Fig. 6. Y y

Fig. 10 is a vertical section through the magnetic clutch taken along the irregular lines l0-l0of Fig. 2. v v

Fig. 11 is a horizontal section taken on irregular lines H .H of Fig. 12. Y Fig. 12 is a vertical section taken on lines I 2I2 of Fig. 11.

Fig. 13 is a vertical section taken on lines l3l 3 0f Fig. 12.

Fig. 14 is a vertical transverse section portion of the mechanism drawn to an enlarged'scale showing the adjustable mounting of lthe grinder head for transverse movement upon the table.

Fig. l5 is a similar view partially in section .illustrating the mounting of the carriage Yand of the stepped drill at the juncture of two steps illustrating thel filleted angle of juncture. Y Fig.v 19 is a similar section illustrating a portion of a drill in which theV shoulder between the two drill steps is concavely ground.

Fig. 20A is a similar sectionrof a portion of a stepped drill hole resulting from use of thev type of step drill illustrated in Fig. 1'1.-y

FigVZ'l is an end yview of a drill blank, a portion v thereof being illustrated fin section, and showing a portion of the grinding wheel in position'at the start of a relief grinding operation. The broken line illustrates the opposite limit of travel of the drill relative to the Agrinder during the rocking of Y tion for reliefv grinding, one broken line indicating n Fig-6is`a side front elevation of aportion of the 5.0 the `completed relief cut and the nearly radial Fig. 26 is a diagrammatic view of the wiring,-

timer, magnetic clutch, etc.

Like numerals refer to like elements throughout the drawings in which |!V designates a supporting base or table mounted upon legs 5| and provided with a floor supported platform 53 upon which is mounted and secured a driving motor M.

This motor transmits rotation to and through the step pulley 55 by a belt 55 t0 a second step -driven-pulley'58 carried by the' main drive shaft 60 journalled in suitable bearings 6| carried by the table 50. A driving sprocket 63 is carried at the outer end of the shaft 60 and, through-chain 64, transmitsrotation to a second sprocket 65 secured to a counter-shaft 66. A clutch generally indicated by numeral 68 is operatively associated with the sprocket 63 and operable bythe `handle through suitable rods and levers to place the sprocket 63 into and out of operative engagement with the shaft 50 and thereby to effect rotation or discontinue rotation of the driving gears and the machine generally. These gears (seeFig. are mounted at one end of the carriage 12 slidably mounted upon 'the base g,

50, being provided with shafts journalled in suitable bearings carried by an end plate 13 (Figs. 1, 2, v3). The lowermostgear-14 of the train is carried upon shaft 66 which is also journalled in the bracket bearings 11 carried by the end of the l,

base 50, the shaft being extended through the base and journalled at its opposite end in a bracket bearing 18. The shaft 66 is splined from .its bearing support in plate 13 to its opposite end for movement relative to gearing carried by it in movement of the carriage12and it functions to feed the; carriage, automatically or manually, longitudinally of the base 50 and to permit movementvof gear 14 which is splined to the shaft 66.

The second gear 80 meshes with gear 14 and is i'- rotated thereby, being mounted upon the stub shaft 8| and, in turn, meshing with the gear 82 with which is integrated the pinion 83 on the shaft 84. The shaft 84 as indicated above is jOulnalled near one'end in the end plate 13 and base 50 and includesja driving motor 96 and a disc like grinder 91, rotatable thereby through pulleys 98, 99 and the belt |00. The bearing block VI 0| carries the'grinder and its driving shaft is in turn carried by the plate |02 which may be r0- tatably adjusted upon the assembly by release of the nut |03 to vary the inclination ofthe grinding wheel 91. Transverse movement of the grinding assembly 95 is effected by means of the hand wheel |01 and the shaft |08 at the front of the table 50, the latter being threadedly engaged with the block 09 carried by the plate 95a which is shouldered to ride upon guide ribs 50a of the table 50, which-latter is provided with an open- .-16.0 14) for transverse or lateral adjustment upon the A' 4 ing at the top to permit movement of the block |09.

The work-head ||0 is' mounted for rocking movement upon the carriage, being provided with a pivot I2 at each end, these pivots being located at near the bottom of the Work head I I0 and coaxial with the axis or rocking movement of the head (Fig. 4). These pivots are journalled in bearing blocks aI |4-which are in turn carried by `the, supporting plate ||5 which is secured as by cap screws I6, to the upper surface of the carriage 12. Projecting from one side of the head ||0 is a plate I|8 secured in a recess ||0a in the bottom of the head ||0 by screws H9. Threadedly engaging the projection ||5a of the plate H51 and 'projecting'upwardlytherethrough, is a stop "screw l'havin'g `a projecting handle |20a whereby it may be rotated and, due to its threaded engagement, raised 'and lowered to limit the rocking movement of the head ||0. An anvil pin ||5b is carried by the projecting portionV ||8a of the plate |I8 over stoppin |20, the upper end of which is in contact at one limit of rocking movement of the work head (Fig. 5) f The plate .H8 projects laterally beyond the other side of the work head .I I0 as indicated by numeral-I I8c (Figs. 3, 4, 5), and-is provided at its outer edge with a depending shouldered plate |25 secured as bysscrews |25ato the plate IIB at its outer edge. The-plate I 25is provided with an inwardly projecting shoulder |25b at its lower edge (Figs. 3, 5) Secured to the carriage 12 and projecting upwardly therefrom is the coil spring seating at its vupper end in a suitable recess the bottom of the plate ||8 (Fig. 5).

Coacting with the coil springi |30 are a pair of supplementary coil springs 3| extending between the plate ||5 and the plate IIB, suitable recesses being provided in such plates to position and seat said springs, which, as willbe apparent, normally act Vto urge the work head I I0 at itspivots I I2 to the position illustrated in Fig. 5 of the anvil pin Ilb in contacty with the stop screwV |20. Movement. of the work head to this position will move 4the work piece carried thereby in a direction away from the grinding wheel 91.

The work head I0 is longitudinaly bored (Figs. v3, 4, 5), to accommodate a bearing sleeve |33 xed therein and projecting from the ends of the work head. The latter, in the embodiment shown, is provided with a transverse slot ||0b at one side between that side and the central bore. Screws |vthreadedly engage a kwork head ||0 above and below the cut |0a and may be adjusted to securely grip the bearing sleeve |33 in its bore. Journalled in the sleeve |33 is a chuck-carrying sleeve |31 projecting beyond the ends of the bearingsleeve as indicated in Fig. 4, for example. At one projecting end the sleeve I 31 is provided with a flange |31a to which is secured, by screws or otherwise, a collar |38 carrying the bearing member |39. Also secured to the flange |3111I is a chuck generally indicated bynumeral |40 provided with any suitable means for gripping and holding a work piece |4I.as, for example, a drill blank. This chuck isprovided with a rearwardly extending flange |40a. seating in the sleeve |31 (Fig. 4). Housed in recesses in one end of the head I|0 are the spring urged pins |45 normally projected from their recesses by the coiled springs |46. The ends of these pins bear against a face of the bearing |39 and urge the chuck |40 on sleeve |31 outwardly to the right as viewed in Fig. 4. The work head ||0 is provided with a threaded entiteitA l. wein .theionoeotral thereof A(Figi 4.1 in which isthroafiotl a easing l 9! oon'trollyborod' and. shoulder dto house. a coil l. ing lll-4d and Provided h. plunger "l5 having.v o eroieotihg knob im and o. cross. ein llltofsoatablo ino tif-oosterse .slot 1.041.. onion the Casing-H14. when one po .Whonthe Plonger isjio the Position ilhistr ed in tithe phi-.will seat in the slot. "Mb and. sor-ieg.- tito willmointaih it in.[Contactwith. a flattened surf aooilg on the slavo 1.3L This outomatioeliy Positions the shook it. is desired. to insert o thiii. or blank. for grihtiihgih propos relation to the members which control the grinding moroiohts. of the. workpiece. During oneration the plunger is lifted. from such position and rotated with the. nih 105.11, resting uponv the; ton. of the casing. |04 (Fig. 5.)... in; which position there is not interference with the rotation of the sleevefll. .At the opposite'end ot sleeve |31 is ,secured the collar |41 as by .Set screws |48, thiscollar carrying the/gear 8.2 Secured thereto as .by threaded nut |50. Collar |41 is provided with anw-extended flange Mgla at the vother. side'and such flange being recessed at |4117. to'clear and surround the adjacent Vend of the sleeve. |33, sucient -clearance being axially provided to permit relative shift ofthe sleeve '|31 in the bearing Asleeveli. A similar clearance is provided attheopposite end as illustrated in Eig. 4.y

'.A lug V||0d is formed" on the top and at one end of'thework head H0.,V being'apertured'to accommodate the '.pin.n |52 (Figs. `3, *4g-15). Journalled ruponith'e(projecting portion of the pin I 52v is an aperturedshoulder |'54a or rocker arm |54,Ythe same being held in' J'ournalled posi-Y tion by the' spacing -r-ing |55V at one side of the shoulder, anda cap |56 at the other end secured to the vpin |52 by-thescrew |51 (Fig. 5).;v V'Intermediate its 'extremities,"the rocker-arm |54 carries a roller |58 above the pin |50. This 'roller lies behind the collar |41 (Figs. 3, '4), and is adapted to bear thereagainst under the actuation ofthe rod- |65 to shiftv the sleeve |31l and chuol;` |40 against the action of the pins |05 toV the e. shoulder litio. slideblvy inthe groove |84@ (Figs.

2.,v 6) .and sorties a lthreaded bolt |67 the head oi which titles. in the T-shaped groove |84b- The treo threaded end. of the bolt |81 projects through the block. |86 and'is engaged by ajout |819 having the, handle |90 projecting therefrom. Intera mediate thenut 1.8.9 andr block |86 is provided a finger |-9| threadedly engagedv by one end of .the rod |65 and apertured to t loosely on the bolt. I -BL `By varying the position of the bloeit 186. with respect tothe pivotal stud |83, the amplitude ofrecriprocating movement of'rod |65 may .be'var-iedas.- desired and` corresponding variations. effected in the rocking movement of thearm |54, with corresponding variation in the amplitude of reciprocation :of` the sleeve .|31 and chuck |40. y i y .A second cam 2li!)` is mounted upon the. shaft H2 (Figs. Y2, 5, 8.)l and'w-ithdt co-actsthe follower '20| carried by `thevarm-202 secured .to-a

shaft200. Theshaft is providedwith an extendingfin'ger-or. lug? 204:1, which overlies the shoulder [25h of plate |25. It'willl be apparent that under. actuation by .camV 200,--the 'shaftz204 will Vb e yoscillated and .the nger- 204a will-bear resistance of the springs |30, |3.I.` This moveleft, as'viewed inY Eig. 4,- for eztample.1 At the y lower endof the arm`|54 is a cross pin |60 extending 'through Vthe recess |54 in theV lower end' oflthe arm |54. Journalledupon this pin |60 is an apertured end ofl the rod' |65 (Figs. 13,v4,`5,6 l i Y Y y The carriage 12 and with it the sjlpported'ele ments of the 'mechanism 'including-'the fworl; head1 |0 are rjnovalole longitudinally by iqtuat'io'ri fconventional lathe-type feed means including the manually operable handle-|68,L shaft |6| in pinion |62 and rack 12a mounted at the bottom of the carriage -12 in a way 50cfformed the basev 50. Y Suitable guiding meansA provided-to prevent lateral displacement of the carriage 12 and to insure ac'curatevlongitudinal movement thereof upon the base 50.*y The same conventional m'eclianism'is availed of for autoingtic longi-` l tudinal feed' of the carriage, `if so desired, by actuation of the knob'lSB. l A n To reciprocate the'vrod |65 for vreciprocatio'n of the chuck and work piece by means of the rocker arm |50, l provide aoam (VFigsHZN, 5,15*), mounted upon and securedto" the shaft 72 (Figs.P 2, 10). Coacting with thecam |10 isthe fl-u lower comprising a roller pivgtally mounted at the upper .endl of a rocking arm |16 (Figs.I 2 and f7) ,ijournalled on a pin |18`and provided with a projecting lug l|1|ia having 'a' soolet therein' within-which is mounted the ball |80,having menty causes a movement of the chuck and work piece toward oir-into the grinding wheel '91 as will beapparent. Y Y" It will benotedlthat the cam v200 is provided withv arcuate slots 20041; through whichI 'project tlneacied` bolts 2|0'which threadedly'engage shoulder |10a on the adjacent camY |10; 1` Ihese bolts and f'slots permit' relative rotative adjust'i men't ofcamf200 with respect to cam |10 and when tightened, secure these cams in adjusted relation. This permits a change in Vthe'timing to conform to changed conditions to be met in the grinding of va drill 'or blank. In Vother words, the reciprocating movement of the work head may be adjustably timed in desired synchro'nisrn with the rocking .movement of such hea-d.` Associated'with the shaft |12 is a magnetic clutch mechanism generally indicated by the' numeral 2|2 (Fig. 10)., comprising a cylindrical casing, in one portion 2`|3 thereof chambered to receive one end of the shaft |12 which ispro-v vided with an enlarged disc portieri |12; 0n either side of this 'disc is provided a clutch ring 2|5,.these plates being loosely mounted'inthe casing and secured against rotation'other than with 'the' casing by pins 2|@ extending through rings 2|5 and into the Wall of the casing portion 2|3. Inserts of suitable materialsuch afs-cork,` asbestoa'brake lining 'or the like, are designated by numeral 2 |1 and carried on the opposed inner ffaces of thering '2|5in lcontact with or'inv proximity to thermes of the dise uzcqriiredeu stops 2|8 aref'carriedf'in the inner f aceiofdthe casingportionl to limit` lthe aiia'l v"movement inorre direction of the adjacent -ring .The olutoh'oasine also oohioilsos Segond' chambered portion2`l9'having an apertured'end 'wall 2|9a"sho'u1dred 'adjacent its outer periphery to aord av seat for the'casing portion 2|3 V(Fig. To the opposite end of the casing portion 2|9 is secured end ange 220 of`the shaft 22|, such securement beingby means of cap screws 222 or the like. The flanged end of the shaft 22| is centrally recessed at 22|a and provided with a bearing sleeve 224 therein, in which is loosely tted'a stub-shaft 226 which is chamber-ed at one end to receive the coil spring 221 bearing against the end of the recess in the shaft 22| to urge such stub-shaft outwardly therefrom. At its outerend, the stub-shaft is enlarged and provided with a flange 228 and a 'pair of spaced flanges 229 which provide'a groove 230. In this groove is mounted the free en'd of each of a pluralityof fingers 23|, such ngers being pivoted at 23| intermediate their'extremities upon pins carried by spaced lugs 233 projecting from the outer face of the ange 2 9a of clutch casing portion 2|9. It will be apparent that movement of the stub` shaft 226 against the action of' the spring 221, i. e., to the left as viewed inFig. 10, will result in a rockingY or a partialrotation of the ngers`23l; These fingers bearing against the outer face of one of the rings 2|5 serve to move the two rings toward each other relatively and to cause'frictional engagement of the portions 2|1 of the disc with the flange |12c and rotation of the clutch casing 2|2 Aand shaft 22| will be' transmitted'tothe shaft |12. i The pins 2|6 are extended into suitable apertures in the end wall 2|9a ofcasing portion2l9: Threaded screws 235 serve to secure'the two cas--y ing portions 2|3,"2|`9 together in assembled re# lation. 'i i i' i'To effect this clutching action just described, I provide electro-magnetic coils 238` in the cas--` inglportion 2|9 and with them are associated magnetic cores 240 projection beyond the coils 238 into proximity with an armatureldisc' 242 which Ais slidablyl mounted 'upon the heads Vof studs 243 carriedV by pins `245 projecting frompthe face of the shaft flange or hub- 220. Intermediate the -magnetic coresV 238 and 'thel armatures `242 is a sheet of insulating material 246. The armature 242 is secured to the stub shaft 226 by a nut 226a. a It will be apparent that when current is-supplied to the magnetic coils 238 magnetism will be generated Yin the cores 240 with the consequent attraction of the armature 242 which is mounted for sufi'icient movement to move theA stub shaft'226 into clutching position. Mounted upon Vthe shaft 22| exteriorly ofthe clutch casing are afpair of slip or commutator rings 250 separated;by an insulatingV disc 25| and mounted in shouldered insulating collars 252, 253 (Fig. 10). Leads 254, 255-extend through the insulating collar 252, one to each of the commutator rings 250, the lead 254 being insulated from one ring as illustrated in FigflO. These leads are suitably connected to the series of coils 238 for excitation thereof by the passage of current therethrough. Brushes 260 connected with suitable current wires ride upon the commutator rings 250 and are in circuit with a source of current (Fig. 2).

- Mounted upon and secured to the shaft |12 in proximity to the cams |10, 200 is a cam disc 265 (Figs. l2, 9). The outer periphery of this disc 265 is provided with spaced depressions 265a.A shown as arcuate in contour. The follower, com prising a roller 266, rides upon the peripherygof @he 1180.165 Whih iS mounted in Ifbrerclst 2,68,

afse'co'nd roller'269 beingfcarried Vaijfth'e lower end of the bracket 268 and seatable in the notch 269a. of a block ZGBD'III'QHnted upon 'the Ycarriage 172. Thebracket `268 is recipro'cable or oscilla-v table inafrecess-Zla in ay supporting bracket 210 (Fig.' 5) 'and the roller 266 is urged into yconi'- stant contact with the cam disc 265 by a spring urged'pin 212 carried in the bracket 210 which is in turn secured b y the bolts 213 to the carriage 12j" Also' 'carriedvby the bracket 210 is'afswitch casing"215 to which lead a pair of current ,wires a; b, (Figs. 2, 26) A switch of any desired type is located in'the casing 215 and is providedfwith aprotruding'spring-urged plunger 215a. When the follower or' rolle'r1266 is riding on the periphery of' the cam 265 out of anydepression 265a, the bracket-'268 will move the switch plunger `21'5aand close the circuit through the wires `b. However, lwhen the roller rides into depression 265a., the bracket 268 will be urged 'into the position illustrated in Figs. 2 and 9 at which tiin the plunger is moved out of circuit-#closing posinon. 4' s f'- l' Associated with themagnetic clutch in the opieration vof thelmechanism` described' is a'timer mechanism generallyindicated by numeral'280 (Figs. 2, 11,' 12) Thiszcomprises the casing'28'l open at one end, -and provided with a recess vat such end-to Vaccommodate the outer edge'iof'the disc 282.: .-'Ihe'outer face of the casing'2'8lfispro2 vided with a'hubv portion 28|a `a'puartured and provided with a tubular -insulating sleeve 283 through which protudes a conductor pinf284 having ahead 284a and yieldinglyurgedbythe coilnspringe285 into :Contact with a conductor rod 286.r On the enclosed faceof the disc 282 is'secured an' insulating block 288 which in 'turn' car-'i ries Yaspring contact 289 normally'in'cntact with the inner end of `the-pin 284. The breaker arm 290 is pivotally mounted on the pin 29| proi jecting'from'the-face of the disc 282'andointer-i mediate its extremities. One end f the breaker arm 290is `extended to overlie an adjustable stop 294 also carriedby the inn-er face -of `thedisc 282. Aninsulating piece 295 is carriedby the breaker 290. The spring 296 bears upon the breaker arm as indicated in Fig. `12 andnormally maintains the same at its end `bearing against the stop 294. At its opposite end, breaker' 290 lis provided with anadjustable screw contact 298 overlying and normally spaced from a` yielding contact 300 journallel' in thel spaced arms 302a of a bracket 302 secured to the Vinner face of the disc 282.Y This contact 300is provided with a; collar 303 secured thereto beneath one of the bracket arms 302a and is held thereagainst b y a coilspring 304 mounted between the two bracket arms.- This arrangement permits the contact pin 300 to yield when necessary against the-action ofkthe. spring 304. A shaft 306, having an enlarged vshoulder 306a, is lprovided and the shoulder'306aris journalled in ay bearing member 301 carried inasuitable recess at the centerof the hub 282m of discI 282. Outwardly of the shoulderportion 306a, the shaft 306 is provided with a reduced end 3061) projecting into the casing 28| where it carries a breaker cam 3|0 secured to it and spaced from the bearing by a washer 3| This -cam3l0 co-acts with the con tact piece 2951 attim-ed intervals during its roe' tation to oscillatethe breaker arm 290 to bring the contacts 298,V 300 to a meeting. Leads c and d extend `from the contact .289 through the Contact pin -300 and from the contact 298 respectively (see Figs.; 1.2, '26`).\ V'Ivlhe cam 3|0 is provided in amaai' which are journalled shouldered portions 320d of.

thltbular shaft320 through which extends the shaft Sus 1oose1y journaued therein. one ena of the shaft 320 is enlarged to provide a chamber in which are mounted bearing members 322 which provide bearing support for an extended sleeve portion 324e, and a clutch disc 324. Thisdisc324 is rotatably mounted Within the cylindrical wall 325a of the knob 325 which is secured as bythe set screw 32B to one end of the inner shaft`306. Springrurged clutching pins 321 are 1housed in suitable radial apertures in the disc 324|A and are urged against the inner wall of the flange 325a in frictional contact therewith. Mounted upon asecond tubular extension 324b surrounding and spaced from a sleeve-portion 324a, is the gear 90 in mesh with gear 89 (Figs. 2, 11). It will be apparent that, normally, rotation of the gear 9U will be transmitted through the lclutch disc 324 and the knob 325 to the shaft 306 -to rotate the breaker cam 3|ll. The disc 282 is provided with an eX- tended hub 282a threadedlysecured tojan extended shoulder portion 320a of the'tubular shaft 320 so that any rotative movement `of shaft`32l] will be transmitted to the timer disc 282, carrying the breaker arm and contacts. The knob 325 mayV with al consequent advance or retardation of the` The purpose of these closingo-f the same leads. adjustments will be made clear below. f1 f I It may be stated here that the primary purpose for providing means for adjustment of the timer casing and disc 282 relative to the shaft 305 and l0 The weight of the rack V330 on plate 33| is sufcient to maintain the roller 33Min contact with the edgeV 34011 during longitudinal movement of the table 12 and it will beI apparent that the cam plate 340 may be adjustably rotated to vary the rate of rise and fall of the rack 330 for any uni form longitudinal movement of the carriage 12, or may be set in horizontalposition sothat there will be no rise and fall of the rack andtno advance `or retardation ofthe timer mechanism, as for grinding work pieces having straight ilutes instead of helical grooves and flutes.

It will be apparent that the timer shaft 306 andl chuck' |40 are driven' from a vcommon shaft 84 and, therefore, rotate in synchronism i. e., at the saine angular rate,v if the gearing be properly selected. l n

YThe cams |10 and 200 are so constructed and arrangedv that the work head and work piece will be rocked and reciprocated in synchronized relation. This synchronized relation is such that the thatfthe work piecewill be at a point most remote breaker cam 3|0 is to compensate for the helical twist or lead of the grooves and flutes on a twist drill, as such drill is moved longitudinally past the grinding wheel 91. Y

The exterior of the tubular shaft 32|] between its shouldered portions 32|! is provided with helical teeth 329c (Fig. 2) which are arranged to mesh with the teeth of a vertically mounted rack 330 mounted upon the vvertically vreciprocable plate 33| mountedb'etween the bearing members -33'3 which is turn are carried upon a plate335 secured to the brackets 3 5. Therpla'te 335 is thus secured 12 for longitudinal movementY to thev carriage therewith.

Beneath the carriage 12, the rack plate 33| is provided with a roller 33Ia. On the front of the base is mounted the semi-cylindrical cam plate 340 pivotally adjustable about the shaft 34| and provided with an arcuate slot 3400, in which rides a friction block 343 carried by the base 50. From one end of the cam plate 340 projects the handle 3401). If convenientthe outer curved portion of the plate 340 may be provided with index markings 340e arranged in proximity to marks on a master block 345 also projecting from the front of the base 50. The upper edge of the plate 3'40d is of straight :line construction, in the embodimentillustrated,V and underlies the roller 33m.

iniits rocking movement from the centero'of the grinding wheel as it encounters the cutting edge and thev land of each -flute of thedrill and at the proper point will be moved further toward and into the grinder wheel to'effect the desired relief cutting between the rear edge of the land and the f trailing edge of the flute.`

By adjustmentof the timing means through knob 325, the'rtiming of the grinding operation may be varied as indicatedin Fig. 24 where the near-radial broken lines indicatevarious points' at which thewo-rk-p'iecev Vmay be moved to-a posil tion laterally most remote from the axis of they grinding wheel 91';V In short, a change in the timing Vmechanism may be effected as desired to obtain lands of any desired width and to effect relief grinding, if so desired, from the cutting edge of the flute without formation of lands.

'v Thereciprocating movement of the head is desirable also during the grinding Yof the lands and relief vofv the flutes as vit eliminatesany grooving or irregularity in such grinding during the longitudinal feed of the work piece past the grinder.

With the automatic compensating rotation of the tubular shaft 320, as described above, the timing of the actuating cams |10, 20'0 is automatically changed to initiate and terminate the grinding 4cuts on the work piece thereby to compensate for'the helical twist or lead of the flutes of such work piece. Y

In Fig. 26 1 have illustrated diagrammatically a Wiring diagram which is suitable to effectr the operation of my machine in which two parallel circuits are illustrated, the one including leads or-wires c, d and the other, the leads or wires a,b, indicating a source of current `or power. -It i will be apparent, from this diagram, that either circuit is adapted to excite thelmagnet 240iof the clutch in which'case rotation of vthe cam shaft will ensue, unless either or both Aof the switchesY t vmechanism is electrically connected to the magnets of the clutch s'o that their excitation by this ycircuit will occur, due to the normal separation of the contacts Fig. 12), only as the lobes 3|0a of the breaker cam 3|0 make the cir-:j cuit at the contacts 298, V300, of the breakerj cam.

The follower 266 when riding on the high sur'- faces of cam 265 will maintain the circuitclsed through the switch in casing 215 and provide for energization of the clutch magnets thereby for rotation of the cam shaft |12 duringthose portions of the travel of the timer cam 3|0where it is out of contact with the `breaker and piece 295. However, as theV follower 266 rides into a depression 265e the switch in casing 215 (which I term the carry-over. switch) l is opened and for a brief period of time the magnetic clutch releases the cam shaft |12 Aand it is brought sharply to rest until the breaker cam 3,10 temporarily closes thecontacts 298, 300 whichagain operate to energize the magnetic clutch for a suicient period of time to rotate the cam 2.65 to bring its follower up on the high, switch-.closing surfaceof the cam.

'Ihearrangernent and operation of the timer and carry-over switch cam .is such that if the grinding of a-work piece is interrupted and rotation `of the chuck andwork piece follows asfby hand, when the magnetic cl-utch is not in clutch-- ing .positionrestart.,A of the grinding will result, automatically, in the proper synchronism and coordination of the rocking-and reciprocating cams. The Samevis true when anew work piece is properly positioned Yin ,they chuck4 for grinding. Y In other words, the cam shaft is always brought to rest with the :follower roller 266 in one of-- the depressions 2651i; Regardless of the position of the breaker cam 3|0when workris again started, the; cam .shaft |12 will not, start rotation with the cams until the breaker-again closes the Vcircuit lthrough the magnetic clutch to initiate rotation ofthe cam shaft and that will be properly timed with jtheposition Voffthe work piece Since the latterisgeared` to and synchronized with the r`driving means forthe breaker, cam,-as eX- plained above.g l

- Bearing in mind `thatvthe rotation of the work piece is in unison or synchronism withthe rotation of the breaker cam 3 I0, properpositioning of the two cams |10, 200 onthe cam shaft |12 perf mit a portionlor all ofY the groove,V of the work piece to rotatelpast the grinder wheel91 duri-ng the temporary dwell or inaction of the cam shaft.

Also, it is to be rnotedthat ywherelands are toVV be'ground upon iiutesatn theirfleading edges, it is essential that the work head ||0, withthe workpiece, be in position farthest removed from the grindingywheelwbut vthereafter the cam' 200 ac-` tuatesk its follower and the rock. shaft 204 to effect therelief grinding of the remainder `of the utevsurface which entails a proper coordination of-the cain200 with the actuation, through the magnetic clutch, of the cam shaft.| 12.f

The two-lobe breaker cam 3| 0 is utilized for the :grinding of a two-flute drill and the rateof rotation imparted to the `work piece and timer` cam is also selected for the grinding of sucha drill, In the embodiment illustrated, `however, each of theV cams y|10 and 2| 0 is provided with three lobes` (although the number may be varied if the proper rate of rotation be correspondingly varied), each lobe relating to therelief grinding of one flute or the shoulder thereof on a two fluted drill. The cams |10 and 2| 0 will rotate 120 del grees While the timer shaft '306 rotates 180 degrees so that the latter, in theform shown, will be rotated three complete revolutions for two complete revolutions'of the cam shaft |12; Inl other words, with each half revolutionxof the timer shaft y306 there will be effected a full reciprocationjof the* chuck anda full rocking movement andreturnof the work head, l f

In order that thecarry-over 'switch follower 266'may properly come: to rest in each depression 2l65a offcam 265, it isdesirable'to make provision for a slight dwell orinterruption of the rotation of the cam shaft. :In\ ,other words,.the,shaft 22| whicnis continuously rotating will overrun or travel a smallamountbefore the magnetic clutch 2|2 is again actuated by thetimer 280 to regrip or clutch theV cam shaft |12. Otherwise, as pointed outu,n1es,s the clutch 68 'hasbeenreleased the timer Vshaft 306, shaft 84,l and chuck |410 are constantlydriven so that the synchronized relation between the clutch casing 2 3--2 9, thetimer,` andthe chuck carrying the A,work lpiece islmaintained.

For the relief grinding fof theishoulder orggstep ofthe drill ,fromfits -leadingedge to its trailing.

edge, it is necessaryV` to advance the work piece A longitudinally ofthe grinderh (underi actuation ofethe springv |85) ,during theperiodgof timeentails theproper'timing ofngthe reciprocating movement of the worklhead `||0 bythe cam |10 so that its follower 12,66wil1 pivot the plate por-- tion ofthe rockerarm-I Z-to thrust the ,rodv |65 inthe direction Yofv the, arrow in,-Fig; .Ll-to permit the` spring urgedpins;.| to advance .the work head `to :the right as viewedJ in'li'g.l 1 to effect relief grinding of the shoulder of 4one fiute'and thereafter` to returnthe work-'head' by apull upon .they rod |65'againstj` the resistance ofthe pins |45 while the fsucceedinggroove of the drill is passing the grinder. This willv again position theworkpiecereadyfor the reliefA grinding of the shoulderpf thejsecond flute. z y y I In, Figs..l6 andl'l I have illustrated a stepped drill ground upon-,the machine ofl this invention in which lrdesignates aiiutefofa twist drill at the leading edge of,which'there has been ground orleft.unground, -a raised land From the rear of ,thelandljfto the .trailing edge of the flute |0` the surface hasbeen ground to provide a relief portion |2-to reduce or eliminate binding ofthe drill .dulinga cutting operation thereby. Likewise, the shoulder|3 has been ground from its leading edge I4 to its trailing edgeY I5' to provide a relief forthe ,cutting edge of the shoulder in grinding operations, In Fig. 21Y I have illustrated adrill in relation to the grinding wheel 91 just after formation of a land and prior to the` grinding, of the :relief `after'said land. Fig.

22-,is a View similar to Fig. 21^showing the relation of the :drill and grindingrwheel at the completion of the relief grinding of 4a flute.

In Fig..23 I have illustrated vin said elevation the position of a drill with respect to the.grind. ing wheel 191 atl the completion of the relief grinding of a ishoulder'as described above.

Itwill be noted Nthat Ihave filleted the juncture 653 of the shoulders and the reduced drill portions as indicatedatv I6, (Figs. 16, 18, 23)'. This is done by proper shapingfthe grinding wheel 91 and preventsthefgformation of burrs at the merger of a reduced drilled holeY with a hole 'of largerdiameter as illustrated `in Fig. 18,y thereby `ob- Viating` theweakening of-the shoulder edge and the necessity foran additional finishing opera- In' some# cases', I desirable to' undercut l thesurface .of-,:theeshouflder asillustrated at1|1 iniFig. 1 9 by a separate operationto enablethe` user of the drill to drill a hole of the character illustrated in Fig. 2,0 where the shoulderbetween the. two-drillA holes is provided with a relatively rased portion i8 (Fig. 20) ,which is of `value in that it greatly facilitates accurate depthgauging of the drilled holes. Y

Itwill be apparent thatin the use of my machine, after proper setting of the workpiece in the chuck to conform to the timed actions of the chuck and work headdescribed above, the Work piece may be moved laterally intoproper relation to the grinding wheel and after aninitial shoulder lforming cut is made, the drill maybe moved automatically or manually, longitudinally vwith respect to the grindenduring which'move-A ment it will be reciprocated and rocked or oscillated relative to the grinding wheel and in proper. ly timed cycles so as to,v obtain the desired lands and reliefs and, in the case of helically fluted drills and the like,the timing will be advanced or retarded to compensate for the helical twist or lead of the fiutes and grooves;y

My invention is susceptibleto modification and variation and I do not wish to be restricted to the specific embodiment illustrated and described eX- cept as the appendant claims, -properly construed with respect to the prior art, compel such restrictions.

I claim: j

1 In mechanism of the class described, a base, a, headmounted thereon for, rocking movement and provided with an engageable'portion, arock shaft having means engageable with saidportion to. rock said head, means to rock said shaft including a rocker arm carried thereby, .a rotating shaft, a cam carried by said shaft, a follower carried by said rocker arm and contactable with said cam, means intermittently to rotate said caml shaft, comprising a drive shaft and an automaticl clutching means interposed between said drive` and cam shafts. 2. In mechanism of theclass described, abase,` a head mounted thereon for'rocking movement andprovided with an-engageable: portion, a rock n shaft having, means engageable. with vsaid por-V tion to rock said head, :means to rocksaid` shaft* ..14 a grinding member vcarried thereby, a work head rockably mounted upon said base, a chuck for carrying a work piece rotatably mounted in s aid head, means to rotate said chuck, means to rock said workv head including an engageable member carriedby said .work head, arock shaft means carried thereby to engagesaid engageable memberto impart rocking movement to said work head,gmeans including acam to rock said shaft, a shaft carrying said cam, means to rotate said lastA named shaft including a drive shaft and a clutch interposed therebetween and said cam shaft, timing means automatically to actuate and re'leasesaid clutch, and means to actuate. said timing; means in synchronism withthe rotation ofsaidchuck. y A ,v A,

;5. Inmechanismofthe class described, albase, a work .head rockably mounted upon said base, a chuck rotatably. mounted in said work head,

means vtorock said work head including v.a rock shaft'engageable with said work head, meansto rock said shaft includingva rocker arm and a cam `oo acting therewith, a shaft carrying said cam, 'a drive-shaft, `clutching means operatively interposed .between said drive-shaft and said cam-shaft, and including clutch members,.mag

netic actuating means therefor, including a magi net andarmature, a circuit including said magnet, a timer also included in said circuit. and comprising normally spaced contactsin said lcircuit and a'breaker arm actuatable to close said contacts, acam coactinggwith said arm to effect Y tionthereby. of said clutch.

including a rocker arm' carried thereby, a'rotating shaft, arcam carried by said shaft, affollower carried bysaid rocker arm and 'contactable with said cam, means intermittently.to'rotate said camshaft, comp-rising a drive shaft and an automatic clutching means. interposed between said drive and cam shafts, and timing means *operablein-V termittently to actuate said clutching means.

3. In mechanism of the class.described, abase, a-head mounted thereon for rocking movement: and provided with an engageable portion, a rock shaft havin-g means engageable with said portion to rock said head, means toprock said shaft including a rocker arm carried thereby, aro-Y tating shaft, a cam carried by said shaftg-afollower carried by said rocker arm and conltactable with said cam, ymeans intermittently said timing means being constructed and ar-`V ranged to operate in synchronism. r l fi. In mechanism of the class described, a base,"

. T6. In mechanism ofthe class; described, a base,

afworkf head rockably mounted upon said base,

a chuck` rotatably mounted in said work head,

means to yrockfsaidwork lhead including a .rock

shaftengageableywith saidwork head, means'to rock-.said shaft. including a rocker arm` and a cam coacting therewith, a shaft carrying said cam ,`a drive-shaft, clutching means operatively interposed between said drive-shaftand said cam-shaft, and including clutch members, mag-v netic actuating means therefor, including l'a magnet and armature, va circuit including said magnet,l altimer ,also included in 4said circuit andy cuit and a breaker arm actuatable to close'saidv contacts, a camcoacting with said arm to effect closure of 'said v.contacts intermittently, and Aa drivefshaft carrying said last named cam, means to'rotate the same to effect excitation of said magnet and clutching of said first named drive shaft to saidY flrst named cam-shaft intermittent-A ly, means including a shaft and gears forv rotation of said chuck, said last named shaft being oper#- atively .connected to said timer cam-shaft wherebythe rotation of said chuck will be in synchro-V nism with `the operationof said timer and the actuation thereby of said clutch,`said shaft and gears for rotation of said chuck being operatively connected to said first named drive shaft whereby' the same is driven in vsynchronism'with the said timer cam shafty and chuck.

'7. In .mechanism of the class described, a base,`

a worlhead rockablyf-mounted upon said base', a chuck rotatably Amounted Ain said workv head, means to rock vsaid` work Mhead including a rock shaft engageable VWithfsaid lwork head, means'to rockfsaidshaft includingv arocker arm-'and a cam coacting -there'with,=fa shaftec'arrying said cam. aldriv'e-shaft, clutching-means operatively interposed -betweenwsaid drive-shaftl and said camshaft, and including clutch members, magnetic actuating means therefor, including a magnet and armature, a circuit 'including said magnet, a timer also includedin` said circuit and comprising normally spaced-contacts-in said circuit andta breakeriarm actuatable to close saidv contacts, a cam-coactingWithf-said armto effect closure of said contacts intermittently, and aldrive-shaft carrying said` lastnamedcam, means to rotate the same to eiect excitationof `said inagnetand clutching of said first named drive shaft to said first named cam-shaft intermittentlyjmeans including a shaft and gears forrrotationof said chuck, said last named shaft being operatively connected tosaid timer cam-shaft whereby the rotation of said chuck will bein synchronism with the'operationof 'said timer andthe actuation thereby of said clutch, said shaft and gears for rotation"of""`saidL chuck Vbeing operatively connected tosaid first named drive shaft whereby the same is drivenin synchronism with the said timer cam shaft andichuck`,"said last named operative connection beingconstru'cted and arranged to'rotate saidrst namedy drive shaft at least slightly when saidl cam shaft is declutched therefrom. I

.8. In mechanism of the class described, a base,

Ia work head rockably mounted upon said base,

a chuck rotatably mounted 'in said work head, means to rock said work head including a rock shaft engageable with said` work head, meansto rock said shaft including -a rockerarm anda cam coacting therewith, a shaft carrying said cam, a drive shaft, clutching means operatively interposed between said drive shaft and said cam shaft', and includingv clutch members, magnetic actuating means therefor, including a magnet andvarmatureya circuit including said magnet, a timer also included in said-circuit and compris-v ing normally spaced contacts in said circuit, a breaker arm actuatable to lclose said contacts, a cam coacting with said arm to effect closure of said contacts intermittently, a drive shaft carry, ing ,said last namedvcam,l meansnto rotate the same tok effect excitation"of said magnet andk clutching of saidrstnamed drivel shaft fto said first named cam shaft'intermittentlyfmeans including a shaftrand gears for rotation of said chuck, said last named shaft being operatively connected to said timer cam shaft whereby the rotation of said chuck will be in synchronism with theggperationofsaid timer and the actuation thereby of said clutch, a second circuitV including said magnet, and means intermittently to make and break said second circuit, said last named means being constructed'and arranged toV close said second circuit through said magnet when said first circuit is broken. Y i Y 9:V In mechanismof the class described, a base, a work head rotatably mounted upon'said base, a chuck rotatably mounted in said work head, means to rock said work headV including a rock shaft engageable with said.V workhead, means to rock said shaft including arocker armand'a cam coacting therewithgrafshaft carryingjsaidcam, aA drive shaft, clutching means operatively interi posed `between said drive shaft;A and Said'cam 516 shaft,vv and including cmtchr members, magnetic actuating means therefor, including'a magnet and armature, a circuit including said magnet, a timer also included in said` circuit -and comprising normally spaced lcontacts in said circuit, awbreakerl arm actuatable to close said contacts, a cam coacting withsaid arm to effect closure of-said contacts intermittently, a drive shaft carryingsaid-last named cam, means to'rotate the sameto effect excitation of said magnet and clutching of said first named'driveshaft toy said first-named ,c am shaft intermittently, means in cluding a shaft and gears forrotation of said chuck,fsaid -last named shaft being operatively connected. toA said timer cam shaft whereby the rotation ofsaid chuck will be in synchronism withethe operationA of said timer and the *actua-w tion thereby of said clutch, a second circuit including said. magnet,andmeans intermittently tormakeand break said second circuit, said last named meansV being-constructed and arranged toclose saidsecond circuit through said magnet Y when said first circuit is broken, and comprising acam carried by said first named cam shaft and a switch member ractuatable by said cam to 'open'Y andvclose said second circuit at predetermined intervals. I y 'Y 10. Inv mechanism of Ythe class described, a base, a work head rockably mounted uponsaid base, a chuck rotatably mounted in said work head,.means to rock said work head including a rock shaft engageable with said work head, means to rock said shaft including a rocker arm andfa-cam coacting therewith, a shaft carrying said cam, a drive shaft, clutching means operatively interposedbetween said drive shaft 'and said ,cam shaft, and including clutch members, magnetic actuating means therefor, including a magnetandfarmature, a circuit including said magnetpcommutator lrings carried by said drive shaft and included in said circuit, a timer also included in said circuit and comprising normally spaced contacts in said circuit, a breaker arm actuatableV to close said contacts, a cam coacting with said arm tov effect closure of saidcontacts intermittently, a drive shaft carrying said last namedV cam, meansto r-otate the same to effect excitation of said magnet and clutching of said first named drive shaft to said first named cam shaft intermittently, means .including a, shaft and gears for rotation of said chuck, said last namedshaft being operatively connected to said timery cam shaft whereby the rotation of said chuck will be in synchronism with the operation of saidrtimer and theactu'ation thereby of said clutch, a second circuit including said magnet, and means intermittently to make and break said circuit, saidlast named means beingrconstructed and arranged .to close said second circuit through said magnet when said'rfirst circuit is broken.

V11. In mechanism of the class described, a'work head', a, chuck carriedfthereby, means to rotate said chuck and mean-sto reciprocate said chuck comprising a rocker arm, a cam, "a follower actuata'ble bysa'idf cam, and vconnecting meansY bel twe'en said follower and rocker arm, 'said `vlast named means comprising a 'pivotally' mounted bell-crank operatively connected to said follower and a connecting rod extendingY between and operatively" connected to' said bell crank and said rocker arm.

`12. In mechanism' of the class described, a work headfachuck lcarried thereby,"means t'o rotate said chuck and means to reciprocate said chuck 75 comprising-,a rockergarm, vav camj'afollower actuatable by said cam, and connecting means between said follower and rocker arm, said last named means comprising a pivotally mounted bell crank operatively connected to said follower and a connecting rod extending between and operatively connected to said bell crank and said rocker arm, and means to vary the connection of said rod to said bell crank to vary the amplitude of movement of said rocker arm.

13. In mechanism of the class described, a work head, a chuck carried thereby, means to rotate said chuck and means to reciprocate said chuck comprising a rocker arm, a cam, a follower actuatable by said cam, and connecting means between said follower and rocker arm, said last named means comprising a pivotally mounted bell crank operatively connected to said follower and a connecting rod extending between and operatively connected to said bell crank and said rocker arm, and means to Vary the connection of said rod to said bell crank to vary the amplitude of movement of said rocker arm, a shaft carrying said cam and means to rotate such shaft, including a drive shaft and a clutch to connect said shafts in driving relation and means for intermittently releasing said clutch to discontinue driving of said cam shaft, said last named means comprising a magnet and armature, clutch actuating means associated with said armature, an electric circuit including said magnet, and timing means intermittently to open and close said circuit.

14. In mechanism of the class described, a work head, means rockably to support said head, a chuck rotatably and reciprocably mounted therein, means to rock said Work head including a cam and cam actuated mechanism, means to reciprocate said chuck comprising a second cam and cam actuated means, said cams being carried by a rotatable shaft, means to rotate said cam shaft including a drive shaft and a clutch interposed between said drive shaft and said cam shaft, a common drive means for said drive shaft and said chuck, timing means intermittently to actuate and release said clutch in synchronism with the rotation of said chuck, said timing means being actuated by said common drive means.

15. In mechanism of the class described, a work head, means rockably to support said head, a chuck rotatably and reciprocably mounted therein, means to rock said work head including a cam and cam actuated mechanism, means to reciprocate said chuck comprising a second cam and cam actuated means, said cams being carried by a rotatable shaft, means to rotate said cam shaft including a drive shaft and a clutch 18 interposed between said drive shaft and said cam shaft, a common drive means for said drive shaft and said chuck, timing means intermittently to actuate and release said clutch in synchronism with the rotation of said chuck, said timing means being actuated by said common drive means, and means automatically to vary the timing of said timing means.

16. In mechanism of the class described, a work carrying head mounted for rocking movement, supporting means therefor, a rotatable work carrier carried by said head, means continuously to rotate said carrier, a grinding means, means to reciprocate said head relative to said grinding means, means to rock said head comprising a shaft, co-acting means carried by said head, said shaft being provided with means intermittently to actuate said co-acting means to rock said head, a rotatable cam, means to rotatably support said cam and means to rotate said cam, and means operatively interposed between said cam and shaft and actuatable by said cam to rock said shaft and thereby actuate said coacting means to rock said head.

17. In mechanism of the class described, a work carrying head mounted for rocking movement, supporting means therefor, a rotatable work carrier carried by said head, means continuously to rotate said carrier, a grinding means, means to reciprocate said head relative to said grinding means, means to rock said head comprising a shaft, co-acting means carried by said head, said shaft being provided with means intermittently to actuate said co-acting means to rock said head, a rotatable cam, means to rotatably support said cam and means to rotate said cam, means operatively interposed between said cam and shaft and actuatable by said cam to rock said shaft and thereby actuate said co-acting means to rock said head, and a spring member to resist rocking movement of said head from normal or rest position.

WALTER UMBDENSTOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,491 Weishampel Aug. 31, 1937 805,170 Thomas Nov. 21, 1905 1,198,613 Bright Sept. 19, 1916 1,323,452 Cogsdill Dec. 2, 1919 1,640,994 Hanson Aug. 30, 1927 2,099,724 C'ogsdill Nov. 23, 1937 2,193,186 Bannister Mar. 12, 1940 

